The overall objective continues to be an understanding of visual receptor and neural processes, both retinal and more central. Psychophysical experiments are proposed, which with mathematical analysis, may reveal the dynamics of the above processes. Neural interactions to be studied will include the dynamics and extent of lateral inhibition and its relation to acuity and velocity detection, and tests of the "channel hypothesis." Computer-controlled stimulus presentation, in color, will permit the study of the relation of lateral inhibition to color-opponent processes, if any. Straight-line stimuli, both single and multiple (gratings) will be used, with versatile temporal control. Issues to be addressed will include adaptation, receptive fields (whether transient or sustained) and their relation to "channels", and the response speed of different color mechanisms.